LLC converters with automatic resonant frequency tracking based on synchronous rectifier (SR) gate driving signals

In this paper, a novel switching frequency control scheme to track the resonant frequency point (f 0 ) is proposed. First, the synchronous rectifier (SR) gate driving signals are well tuned with proposed universal adaptive SR driving scheme by eliminating the body diode conduction. Then, the novel pulse width locked loop with digital implementation is presented to minimize the pulse width difference between main switch and well tuned SR gate driving signals, making LLC always operate at f 0 point.